In internal combustion engines utilized in portable handheld tools, the use of light metal alloys is increasing in order to keep the weight of the tool within tolerable limits. This leads to critical conditions at the supporting faces of components of different materials in the presence of heat and these conditions can affect the function of the components.
Accordingly, for small internal combustion engines such as two-stroke engines for portable handheld tools, it is known to fix a crankshaft bearing made of steel by means of a bearing cover made of light metal such as a magnesium alloy with the crankshaft bearing being mounted in a bearing seat of an upper portion of a crankcase housing. However, the bearing cover expands considerably more than the crankshaft bearing in the presence of heat because of the different materials so that the press fit of the crankcase bearing in the bearing seat is endangered.
The cast bearing cover is very precisely machined to within a few microns in order to maintain the press fit within a tight temperature range. This machining operation is complex and time consuming and increases the cost of the bearing cover considerably.
Even with a bearing cover which is machined to high precision, a loosening of the press fit or even a clearance between the bearing cover and the crankcase bearing cannot be excluded because of the high temperatures (approximately 120.degree. C.) which develop when the engine is operating in the range of maximum load.